Evaluation of Emotions From Salivary Molecular Biomarkers in an Architectural Context

Architecture influences our well-being, and people's behavior and mood changes in different spaces are directly related to the architectural qualities of the built environment. For example, noise and lack of vegetation can generate stress and stress associated with the built environment can even negatively impact life expectancy. Moreover, psychology, and more specifically emotional regulation, plays a fundamental role in how individuals perceive and react to their environment. Emotional regulation is closely linked to the attachment style developed during childhood. Studies have shown that insecure attachment is associated with poorer emotional regulation, which can amplify stress reactions in response to an environment perceived as hostile or inadequate. Neuroarchitecture is a discipline that combines neuroscience and architecture to design spaces adapted to the psychological and physiological needs of users. Its main objective is to create environments that positively influence emotions and well-being, taking into account how our brain perceives and reacts to different elements of space. Several studies related to neuroarchitecture have been conducted according to different architectural parameters such as style, natural environment, lighting, color, and sunlight pattern. These studies generally use tools such as self-assessment scales (e.g., PANAS for affect), functional magnetic resonance imaging (fMRI), electroencephalogram (EEG), and heart rate measurement. These often subjective or indirect methods require trained and/or medical personnel and heavy equipment. In addition, emotions and their regulation are influenced by several sociodemographic factors, including age and the development of the prefrontal cortex, but also gender, socioeconomic level, education level, and cultural context. These factors modulate exposure to stress, the available regulation strategies, and their effectiveness. Life history, particularly early exposure to traumatic events, is also determining. These elements justify the attention paid to inclusion and exclusion criteria in the study (particularly age, gender, cultural context, etc.) to best control these variables. Recent studies show that emotional states (positive and negative) can also be evaluated by physiological responses. This physiological regulation comes from the action of enzymes and hormones that represent the activity of the autonomic nervous system. Thus, several studies using the Trier Social Stress Test (TSST) have highlighted an increase in the concentration of cortisol, DeHydroEpiAndrosterone (DHEA), and salivary alpha-amylase in response to a state of acute stress and anxiety in tested individuals. Glenk et al. studied 40 adults (21 to 34 years old, allergic or not) using measures such as the State-Trait Anxiety Inventory (STAI-S) (20 self-reported items), the Emotion Regulation Questionnaire (ERQ), a visual analog scale of perceived stress (VAS), salivary cortisol measurements, and plasma oxytocin. Izawa et al. analyzed salivary DHEA levels, blood pressure, and heart rate in 33 students with an average age of 22. Van Stegeren et al. measured salivary cortisol and alpha-amylase in 80 adults (men and women) exposed to TSST. Furthermore, an association between positive emotions and a decrease in salivary cortisol has also been described by Lai et al. in 80 adults via a questionnaire and salivary cortisol analysis. Oxytocin modulates the integration of emotional information and interacts with the reward pathway. It is released during positive social interactions and can downregulate stress and heart rate (study of 163 young adults under 35, high school level, no medication, questionnaires, filmed interviews, blood oxytocin measurement). Finally, Kanen et al. showed that fluctuations in serotonin concentration can generate various emotional phenotypes, highlighting the neurobiological impact on emotional regulation. It is therefore essential that participation in architectural exposure is voluntary, as the perception of control is a key factor in modulating the emotional response. Finally, measuring specific biomarkers (enzymes, hormones) through non-invasive biological tests in saliva provides reliable physiological data on an individual's emotional state). These approaches have already been applied to analyze the effects of olfactory stimuli (study of 170 participants, questionnaires, and salivary biomarkers) or architectural. The objective of the proposed research is therefore to measure, in an immersive context (architecture festival), salivary molecular biomarkers known to be linked to emotions. These measurements are intended to objectively measure the influence of an architectural context on physiological parameters related to emotions, while taking into account the psychological, sociodemographic, and developmental factors identified through a dedicated questionnaire.